The warm summer weekend at the lake brought out sailors, wake boarders and even some old-time slalom water skiers. The discussion on more than one dock also focused on an additional tax on second homes.

"I'm going to put this place on the market before Labor Day," a big, bearded man said. "And hope to close the deal by the end of the year. There's no way I want to pay the extra tax Obama's put on us for 2013."

The truth is, unless the man has significant income, he -- along with 97 percent of the United States population -- will pay no additional tax on a second home in 2013. The new 3.8 percent tax on some investment income that will take effect in January 2013 will hit those taxpayers with adjusted gross incomes over $200,000 a year ($250,000 for married couples filing jointly).

Adjusted gross income is the number at the bottom of the front page of Form 1040. It includes dividends, interest capital gains, wages and retirement income, plus results from partnerships and small businesses. It does not include itemized deductions such as mortgage interest and charitable gifts or personal exemptions.

The tax is complicated, but it can be viewed as a flat tax on investment income above the $250,000/$200,000 threshold. While the tax applies only to investment income above the threshold, other income -- such as wages or Social Security -- can raise adjusted gross income, making investment income more vulnerable to the tax.

For example, let's say a widow earns a combined $60,000 from Social Security and her husband's pension. Needing to scale down, she sells her longtime home for a $400,000 gain, $250,000 of which is excluded from capital gains tax. Then, she sells their golf course condo for a $70,000 gain, all of which is subject to tax. The sale of the two properties would push her adjusted gross income to $280,000 ($150,000 plus $70,000) and into the new 3.8 percent extra tax bracket.

The new tax was passed by Congress in 2010 with the intent of generating an estimated $210 billion to help fund President Obama's health care and Medicare plans. It was recently upheld in a controversial ruling by the Supreme Court.

Second homes that are not rented out and used only as a second residence have always been subject to capital gains tax on any gain. Also, gain is a net number. It is not the simply the difference between the original purchase price and the eventual sales price. Homeowners can subtract real estate commissions, excise tax, and capital improvements before arriving at a net figure for capital gains purposes.

If the home is not rented out and thus not an "investment property," it is ineligible for a tax-deferred exchange.

A person's primary residence still retains its favored status -- even for those who have high incomes. The new "Medicare" tax still won't apply to the first $250,000 on profits from the sale of a personal residence -- or to the first $500,000 in the case of a married couple selling their home. The entire exemption on the sale of a primary residence remains intact and can be claimed every two years.

For example, let's suppose John and Sue McCarthy work full time. They own a beach home that they purchased for $275,000. They have never rented it out. They sell it for $335,000 in 2013. In 2013, they also have earned income from other sources of $225,000. The 3.8 percent 2013 tax would apply as follows: